1. Field of the Invention
The present invention relates to the technical field of touch panels and, more particularly, to an electronic device with touch control circuit powered by dedicated power source.
2. Description of Related Art
The conventional touch display panel includes a touch panel and a display unit overlapped with the touch panel. The touch panel is configured as an operation interface. The touch panel is transparent so that an image generated by the display unit can be viewed directly by a user without being sheltered by the touch panel. Such well known skill of the touch panel may increase additional weight and thickness of the touch display panel, and may further reduce the light penetration rate, and increase reflectance and haze of the touch display panel.
On-cell and in-cell touch technology were invented to overcome the drawbacks of traditional touch technology described above. The on-cell technology is to dispose a sensor on the back side of a color filter substrate to form a completed color filter substrate. One of the on-cell touch technologies is provided to dispose a touch sensor on a thin film and then bond the thin film onto the upper one of the two substrates. The in-cell technology is to dispose the sensor within the LCD cell structure. However, when the sensor is disposed within the LCD cell structure, the distance between the sensor and the common voltage layer is only several micrometers and thus the capacitance induced therebetween is greatly increased, such that, in comparison with such a large capacitance, the capacitance change caused by touch is too small to be detected. Furthermore, because of the short distance, the display signal may be seriously interfered, resulting in a bad display quality.
FIG. 1A schematically illustrates the transparent electrode structure of a single-layer touch panel. As shown, there is a plurality of transparent electrodes 11 arranged in rows and columns, and the electrical signal sensed by one transparent electrode 11 is transmitted through a corresponding conductive wire 12 for output. Such a single-layer transparent electrode structure can realize an actual multi-touch detection. In use, the single-layer transparent electrode structure of FIG. 1A is combined with a display panel. However, when the single-layer transparent electrode structure is integrated to the inside of a display panel, there will be an obvious capacitance produced between the single-layer transparent electrode structure and a common voltage (Vcom) layer of the display panel, which may cause noises to be produced and thus lower the accuracy in detection the touch position. Therefore, it is known that the touch control circuit, particularly the touch control circuit of the in-cell touch panel, is highly susceptible to noises, and accordingly its design has to avoid the noise interference as much as possible.
FIG. 1B is a schematic diagram illustrating how a touch control circuit is interfered by noise. As shown, in an electronic device such as a smart phone, a touch control circuit chip 13 is connected to a sensor electrode 15 through a conductive wire 14 for sensing analog signal generated by a finger's touch. In addition, a microprocessor 16 in the electronic device is connected to another circuit chip 18 or the touch control circuit chip 13 through a connection wire 17 in order to transmit digital signal for providing a corresponding function of the electronic device. For an in-cell touch structure, the microprocessor can be replaced with an LCD display driving circuit and a common voltage layer. Since the electronic devices tend to be compact, the conductive wire 14 and the connection wire 17 are typically very close to each other. Moreover, the touch control circuit chip 13, the microprocessor 16, and the another circuit chip 18 in the electronic device are powered by a single battery power source. As a result, the analog signal of the conductive wire 14 is likely to be interfered by the control signal of the connection wire 17, resulting in an error on touch sensing.
Therefore, it is desirable to provide an improved touch control circuit to an electronic device to mitigate and/or obviate the aforementioned problems.